jsonschema

jsonschema Creates a json schema from a struct

This package can generate a json schema for a struct that is compatible with https://json-schema.org/

type ExampleStruct struct {
  Name string
  Field []int
  SomeOtherStruct OtherStruct
}

func main() {
  defsMap := map[string]jsonschema.Property{}
  schema, err := jsonschema.From(
    ExampleStruct{},
    "#/$defs/",
    func(key string, value jsonschema.Property) {
      defsMap[key] = value
    },
    func(key string) bool {
      _, ok := defsMap[key]
      return ok
    },
    nil,
  )

  if err != nil {
    log.Fatal(err)
  }

  schema.Defs = defs
}

Default applied rules:

• A struct field is labeled as required when the data cannot be nil so strings,bool,int,float,struct, etc.. are required and []string, [8]int, *int, map[string]string are not required. You can overwrite this behavior by using jsonSchema struct tag

Supported struct tags:

• json:
  • "-" Ignores the field
  • "other_name" Renames the field
• jsonSchema:
  • "notRequired" Set the field are not required (by default all fields with the exeption of ptr, array, slice and map are set as required)
  • "required" Set the field as required
  • "deprecated" Mark the field as deprecated
  • "uniqueItems" Every array entry must be unique (Only for arrays)
  • "hidden" Do not expose field in the schema
  • "min=123" Set the minimum value or array length for the field
  • "max=123" Set the maximum value or array length for the field
• description:"describe a property here" Set the description property

You can also chain jsonSchema tags using , for example: jsonSchema:"notRequired,deprecated"

Custom (Un)MarshalJSON

Sometimes you might want to define a custom schema for a type that implements the MarshalJSON and UnmarshalJSON methods.

You can define a custom definition like so:

var PhoneNumber string

func (PhoneNumber) JSONSchemaDescribe() jsonschema.Property {
	minLen := uint(3)
	return jsonschema.Property{
		Title:       "Phone number",
		Description: "This field can contain any kind phone number",
		Type:        jsonschema.PropertyTypeString,
		Examples: []json.RawMessage{
			[]byte("\"06 12345678\""),
			[]byte("\"+31 6 1234 5678\""),
		},
		MinLength: &minLen,
	}
}